Unconjugated serum estriol (E3), cortisol, progesterone, glucose and insulin will be measured every hour for 24 hours and statistically analyzed in hospitilized patients with uncomplicated pregnancies prior to elective repeat cesarean section and in insulin-dependent diabetics between 36 and 38 weeks' gestation in an effort to delineate diurnal variations in serum E3 and to investigate their possible mechanism(s). Subhourly variations of unconjugated serum E3 in late pregnancy will be determined in order to assess whether a single blood specimen suffices for antepartum fetal surveillance instead of multiple blood sampling. Prospective studies assessing the clinical value of unconjugated plasma E3 in diabetic and in prolonged pregnancies will be continued and completed. The value of total and unconjugated plasma (serum) E3 in the management of pregnancies complicated by hypertension and/or intrauterine growth retardation will be determined.